Method and apparatus for osteosynthesis

ABSTRACT

A proximal humeral plate assembly can include a first plate, a coupler, a second plate, and a guide. The first plate can define a window and can have a first major surface adapted to conform to a native bone structure. The coupler can be formed on a second major surface of the first plate opposite the first major surface. The second plate can be adapted to engage the coupler, to cover the window, and to conform to the native bone structure. The second plate can include through holes adapted to receive bone screws. The guide can be adapted to engage the coupler and to guide at least one of a cutting tool and a dilation tool.

FIELD

The following relates to orthopaedic bone plates, and more specifically,relates to plates for reducing and fixing a fractured proximal humerus.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and does not constitute prior art.

Orhthopaedic bone plates have been developed for osteosynthesis, or thereduction and fixation, of complex fractures in the proximal humerus.Typically, anatomic reduction is performed on fragments of a bone beforefixing the fragments to the bone via plates and fasteners. The fragmentsare then fixed to the bone while the bone heals to improve anatomicalignment of the fragments and minimize anatomic congruities anddysfunction. However, anatomic reduction tends to leave a void adjacentto a realigned or repositioned fragment. Voids that remain afteranatomic reduction impede healing, increasing rates of nonunion,malunion, and avascular necrosis.

Thus, there is need for procedures and plating assemblies thatfacilitate filling voids created by performing anatomic reduction onbone fragments. Filling voids that remain after performing anatomicreduction promotes healing by, for example, restoring vascularity tobone fragments.

SUMMARY

A proximal humeral plate assembly can include a first plate, a coupler,a second plate, and a guide. The first plate can define a window and canhave a first major surface adapted to conform to a native bonestructure. The coupler can be formed on a second major surface of thefirst plate opposite the first major surface. The second plate can beadapted to engage the coupler, to cover the window, and to conform tothe native bone structure. The second plate can include through holesadapted to receive bone screws. The guide can be adapted to engage thecoupler and to guide at least one of a cutting tool and a dilation tool.

A method for osteosynthesis of a fracture in a proximal humerus caninclude fixing a first plate to the proximal humerus when a fracturedportion of the proximal humerus is anatomically aligned and accessiblethrough a window included in the first plate, engaging a guide with acoupler formed on the first plate, removing a lateral cortex of theproximal humerus using a cutting tool inserted through a hole in theguide, and filling the dilated cancellous portion of the proximalhumerus by delivering a filler through the hole in the guide.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is an exploded isometric view of a first exemplary bone plateassembly according to various teachings of the present disclosure;

FIG. 2 is a plan view of the bone plate assembly of FIG. 1;

FIG. 3 is a sectional view of a main plate included in the bone plateassembly taken along the line 3-3 of FIG. 1;

FIG. 4 is a plan view of the main plate of FIG. 3 attached to a bone;

FIG. 5 is a perspective view of the main plate and a bone of FIG. 4 anda guide according to various teachings of the present disclosure;

FIG. 6 is a perspective view of the main plate, bone, and guide of FIG.5 and a dilation tool according to various teachings of the presentdisclosure;

FIG. 7 is a perspective view of the main plate, bone, and guide of FIG.5 and the dilation tool of FIG. 6 inserted into the bone and aligned viathe guide;

FIG. 8 is a cross-sectional view of the main plate, bone, guide, anddilation tool taken along the line 8-8 of FIG. 7;

FIG. 9 is a perspective view of the bone plate assembly of FIG. 1 and areconstructed bone according to various teachings of the presentdisclosure;

FIG. 10 is a cross-sectional view of the bone plate assembly andreconstructed bone taken alone the line 10-10 of FIG. 9; and

FIG. 11 is an exploded isometric view of a second exemplary bone plateassembly according to various teachings of the present disclosure.

DESCRIPTION OF VARIOUS EMBODIMENTS

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

Referring to FIGS. 1 through 3, a bone plate assembly 100 is illustratedaccording to various exemplary embodiments of the present disclosure.The bone plate assembly 100 can include a first or main plate 102, asecond or cover plate 104, main plate bone screws 106, cover plate bonescrews 108, an main plate Kirchner wire (K wire) 110, an cover plate Kwire 112, and set screws 114. The main and cover plates 102, 104 can beshaped to substantially or generally conform to or mate with aplate-engaging surface of a bone, such as a lateral surface of aproximal humerus.

The bone screws 106, 108 can be inserted into the main and cover plates102, 104, respectively, to attach the main and cover plates 102, 104 toa bone. The K wires 110, 112 can be inserted into the main and coverplates 102, 104, respectively, to hold bone fragments together and toposition the bone fragments. Set screws 114 can be used to fasten thecover plate 104 to the main plate 102 when the main plate 102 is fixedto a bone.

The main plate 102 can include a first end 116, a second end 118, anouter edge 119, a first or screw-receiving surface 120 opposite a secondor bone-engaging surface 122, screw holes 124, a slot 126, a pin hole128, an opening or window 130, and partial holes 132. The main plate 102can be sized to generally cover a plate-engaging surface of a bonewithout extending beyond the plate-engaging surface. In this regard, thefirst end 116 can have a greater width than the second end 118 such thatthe first end 116 generally covers the head of a bone while the secondend 118 generally covers the neck of the bone.

The width of the first end 116 can be greater than the width of thesecond end 118 and the outer edge 119 can be rounded to prevent scarringof soft tissue. In various embodiments, the main plate 102 can have auniform thickness and a side profile of the main plate 102 can be shapedto conform to a plate-engaging surface of a bone. Alternatively, themain plate 102 can have a varying thickness, the second surface 122 canbe shaped to conform to a plate-engaging surface of a bone, and thefirst surface 120 can be shaped differently than the second surface 122.

The screw holes 124 receive the screws 106 to fix the main plate 102 toa bone. The screw holes 124 can be positioned adjacent to the first end116 of the main plate 102, as shown, or can be positioned elsewhere inthe main plate 102. Although three screw holes are shown, the main plate102 can include more or less screw holes. The screw holes 124 can bethreadless counterbores, as shown. Alternatively, the screw holes 124can be threaded and can be straight or countersunk.

The slot 126 receives one or more of the screws 106 to fix the mainplate 102 to a bone. The slot 126 can be positioned adjacent to thesecond end 118 of the main plate 102, as shown, or can be positionedelsewhere in the main plate 102. The slot 126 can extend substantiallyalong a longitudinal axis x of the main plate 102. The screw 106 can beinserted into the slot 126 first to axially adjust the main plate 102,and then the screws 106 can be inserted into the holes 124 to fix themain plate 102. The slot 126 can be a threadless couterbore, as shown.

The pin hole 128 receives the K wire 110 that holds bone fragmentstogether. The pin hole 128 can be positioned adjacent to the first end116 of the main plate 102, as shown, or can be positioned elsewhere inthe main plate 102. Although one pin hole is shown, the main plate 102can include more or less pin holes. The pin hole 128 can be normal tothe first surface 120 of the main plate 102, as shown, or can be angledrelative to the normal of the first surface 120. The pin hole 128 can beangled toward the first end 116 of the main plate 102 as the pin hole128 extends from the first surface 120 to the second surface 122.Angling the pin hole 128 in this way allows the K wire 110 to extendcloser to an end of a bone proximate to the first end 116 of the mainplate 102.

The window 130 can extend along the longitudinal axis of the main plate102 and can receive the cover plate 104. The window 130 can includelongitudinal sides 133 that extend generally parallel to the outer edge119 between rounded corners of the main plate 102. To this end, the endwidth of the window 130 closest to the first end 116 of the main plate102 can be greater than the end width of the window 130 closest to thesecond end 118 of the main plate 102.

The partial holes 132 receive the set screws 114 to secure the coverplate 104 to the main plate 102. The partial holes 132 can be positionedat the rounded corners of the window 130, as shown, or can be positionedat other locations adjacent to the window 130. Although three partialholes are shown, the main plate 102 can include more or less partialholes. The partial holes 132 can include at least part of a counterboreand a threaded bore, as shown. Alternatively, the partial holes 132 caninclude at least part of a countersink and a threaded bore.

With particular reference to FIG. 3, the main plate 102 can also includeribs 134 having I-shaped cross sections 135, and a coupler or slidemechanism 136 having two L-shaped cross sections 137. The ribs 134 areon either side of the window 130 and extend between the longitudinalsides 133 of the window 130 and the outer edge 119 of the main plate102. The I-shaped cross section 135 increases the strength of the mainplate 102 along the length of the window 130, offsetting strengthreduction in this region due to a reduced cross-sectional area. The ribs134 and the slide mechanism 136 can have rounded corners to prevent softtissue damage.

The slide mechanism 136 can be formed on the first surface 120 of themain plate 102 such that the L-shaped cross section 137 extends outwardfrom the first surface 120 and laterally toward the longitudinal axis xof the main plate 102. The slide mechanisms 136 and the first surface120 can define longitudinal channels 138 that extend substantiallyparallel to the longitudinal sides 133 of the window 130. Alternatively,the slide mechanism 136 and the longitudinal channels 138 can besubstantially parallel with the longitudinal axis x of the main plate102.

The cover plate 104 can include a first end 139, a second end 140, afirst surface 142 opposite a second or bone-engaging surface 144, screwholes 146, a pin hole 148, slide rails 150, and partial counterbores152. The cover plate 104 can be sized to fit within the window 130 inthe main plate 102. In this regard, the outer perimeter of the coverplate 104 can conform to or mate with the inner perimeter of the window130 in the main plate 102. In addition, the cover plate 104 cangenerally cover the window 130 in the main plate 102 when the coverplate 104 is placed within the window 130. The cover plate 104 can havea uniform or varying thickness matching the thickness of the main plate102.

The first and second ends 139, 140 of the cover plate 104 can be roundedto conform to the rounded corners of the window 130 in the main plate102. The first and second surfaces 142, 144 of the cover plate 104 canhave a contour that matches the contour of the first and second surfaces120, 122 of the main plate 102. To this end, the first and secondsurfaces 142, 144 of the cover plate 104 can provide a gradualtransition between portions of the first and second surfaces 120, 122 ofthe main plate 102 on opposite sides of the window 130 in the main plate102. As with the second surface 122 of the main plate 102, the secondsurface 144 of the cover plate 104 can be shaped to conform to aplate-engaging surface of a bone. In addition, the main and cover plates102, 104 can be bendable to conform to a surface of a bone.

The screw holes 146 receive the screws 108 to fix the cover plate 104 toa bone. The screw holes 146 can be positioned at various positions alongthe length of the cover plate 104, as shown, or can be positionedelsewhere in the cover plate 104. Although four screw holes are shown,the cover plate 104 can include more or less screw holes. The screwholes 146 can be threadless counterbores, as shown. Alternatively, thescrew holes 146 can be threaded and can be straight or countersunk.

The pin hole 148 receives the K wire 112 that holds bone fragmentstogether. The pin hole 148 can be positioned adjacent to the first end139 of the cover plate 104, as shown, or can be positioned elsewhere inthe cover plate 104. Although one pin hole is shown, the cover plate 104can include more or less pin holes. The pin hole 148 can beperpendicular to the first surface 142 of the cover plate 104, as shown,or can be angled relative to the normal of the first surface 142. Thepin hole 148 can be angled toward the first end 139 of the cover plate104 as the pin hole 148 extends from the first surface 142 to the secondsurface 144. The pin holes 128, 148 can be positioned generally in thecenter of the plates 102, 104 along the longitudinal axis x wheremultiple bone fragments can reside when the plates 102, 104 are fixed tobone.

The slide rails 150 can be formed on the first surface 142 of the coverplate 104 and can be shaped and sized to engage the longitudinalchannels 138 defined by the slide mechanism 136 and the first surface120 of the main plate 102. In this regard, the slide rails 150 can haverectangular cross-sections and can extend laterally beyond longitudinalsides of the cover plate 104. The distance by which the slide rails 150extend beyond the longitudinal sides of the cover plate 104 can equalthe depth of the longitudinal channels 138. The slide rails 150 can havea length equal to the length of the longitudinal channels 138, and canbe positioned to engage the longitudinal channels 138 when the coverplate 104 is placed within the window 130.

The partial counterbores 152 in the cover plate 104 cooperate withpartial holes 132 in the main plate 102 to form a complete counterboreand a threaded bore that receive the set screws 114 to secure the coverplate 104 to the main plate 102. The partial counterbores 152 provide arecess for the set screws 114 to fit within while securing the coverplate 104. The position and number of the partial counterbores 152 cancorrespond to the position and number of the partial holes 132. Thepartial counterbores 152 can complete the partial counterbores of thepartial holes 132, as shown.

Referring to FIGS. 4 through 11, a method for reduction and fixation ofa proximal humerus 154 using a bone plate system according to variousexemplary embodiments of the present disclosure will now be described. Abone plate system according to the present disclosure can includevarious features of the bone plate assemblies 100, a guide 164 (FIGS. 5through 7), and a bone plate assembly 100′ (FIG. 11). The proximalhumerus 154 has a head 156, a neck 158, a body 160, and a fracture 162.The fracture 162 can be a two, three, or four part head fracture.

With particular reference to FIG. 4, the main plate 102 can bepositioned on the proximal humerus 154 such that the fracture 162 isvisible through the window 130 in the main plate 102. The main plate 102can be positioned such that the window 130 provides access to afractured portion of the proximal humerus 154 adjacent to the fracture162. The bone screws 106 can then be inserted through the screw holes124 and the slot 126 in the main plate 102 and into the proximal humerus154 to fix the main plate 102 to the proximal humerus 154. Before fixingthe main plate 102 to the proximal humerus 154, displaced bone fragmentsof the head 156 resulting from the fracture 162 can be repositioned orrealigned to an anatomically correct position.

With particular reference to FIGS. 5 through 7, the guide 164 caninclude a base 166 having longitudinal edges 167 and a hollow shaft 168defining a passage 170. The base 166 can be shaped and sized to engagethe slide mechanism 136. To this end, the base 166 can be rectangular,and the longitudinal edges 167 can extend laterally outward from one endof the base 166 to another or can be substantially parallel to thelongitudinal axis x of the main plate 102. In addition, the thickness ofthe base can be equal to the height of the longitudinal channels 138.

The hollow shaft 168 can be fixed normal to the base 166 or at apredetermined angle other than ninety degrees relative to the base 166.Alternatively, the hollow shaft 168 can be joined to the base 166 via arotatable socket such that the angle between the hollow shaft 168 andthe base 166 can be adjusted as desired. The passage 170 in the hollowshaft 168 can be sized to receive a cutting tool and/or a dilation tool.The cutting tool can be a burr, a drill, or a saw, and the dilation toolcan be a tamp or a punch.

The guide 164 can slidably engage the slide mechanism 136 to positionthe passage 170 as desired. When the longitudinal channels 138 of themain plate 102 and the longitudinal edges 167 of the guide 164 extendlaterally outward in the direction toward the first end 116 of the mainplate 102, the narrowing distance between the longitudinal channels 138can act as a stop when the base 166 of the guide 164 is inserted in thedirection away from the first end 116 of the main plate 102, as shown.When the longitudinal channels 138 of the main plate 102 and thelongitudinal edges 167 of the guide 164 are parallel, the guide 164 canslide through the length of the slide mechanism 136 without encounteringa stop. The passage 170 can be positioned at a desired insertion graftinsertion site.

With particular reference to FIGS. 6 through 8, when the guide 164 ispositioned in a desired position, such as adjacent to a void remainingafter realigning fragments of the proximal humerus 154, a tool 172 canbe inserted into the guide 164. The tool 172 can include a head 174 anda shaft 176 extending from the head 174. The tool 172 can be a cuttingtool, such as a burr or saw, which is operable to remove a lateralcortex 177 of the proximal humerus 154 corresponding to the passage 170in the guide 164. The lateral cortex 177 can be preserved when removedby, for example, removing the lateral cortex 177 in a single piece.

The tool 172 can also be a dilation tool, such as a tamp or punch, whichis operable to dilate or tamp cancellous bone in or near a voidremaining after realigning displaced bone fragments of the proximalhumerus 154. In this regard, the tool 172 can dilate the void to a knownshape and size such that a bone filler 178 can be shaped and sized tofill the void. The bone filler 178 can be shaped and sized based on theportion of the tool 172 extending into the proximal humerus 154 when thehead 174 of the tool 172 contacts the hollow shaft 168 of the guide 164.

The tool 172 can be a delivery tool, such as a syringe, that is operableto deliver bone filler into the void. In this regard, the bone filler178 can be bone graft, bone crush, bone cement, or osteobiologics thatcan be delivered through the passage 170 of the guide 164 to fill thevoid in the proximal humerus 154. The bone filler 178 can also be shapedand sized before being delivered to the void based on a measured depthof the dilated void. To this end, the bone filler 178 can be bone graft,such as a fibula allograft, that can generally maintain a shape thatfills the void. The tool 172 can tamp solid allograft through the guide164.

A cutting block can be used to cut the bone filler 178 to theappropriate shape and size to fill the void. In this regard, the cuttingblock can cut a lateral end 180 of the bone filler 178 at an angle suchthat the lateral end 180 of the bone filler 178 is generally flush withthe lateral surface of the proximal humerus 154 when the bone filler 178is placed within the void. The angle can be selected based on the angleof the passage 170 relative to the lateral surface of the proximalhumerus 154. A medial end 182 of the bone filler 178 can be left uncut(FIG. 10).

With particular reference to FIGS. 9 and 10, when the void has beenfilled with the bone filler 178, the removed lateral cortex 177 of theproximal humerus 154 can be replaced and the cover plate 104 can besecured within the window 130 of the main plate 102. The slide rails 150of the cover plate 104 can engage the longitudinal channels 138 as thecover plate 104 is inserted in the direction toward the second end 118of the main plate 102. When the longitudinal channels 138 and the sliderails 150 extend laterally outward in the direction toward the first end116 of the main plate 102, the longitudinal channels 138 can act as astop when the cover plate 104 is slidably inserted in the directiontoward the second end 118 of the main plate 102. Alternatively, thelongitudinal channels 138 and the slide rails 150 can be substantiallyparallel with the longitudinal axis x of the main plate 102 and thecover plate 104 can be supported by the main plate 102 within the window130.

The bone screws 108 can be inserted through the screw holes 146 in thecover plate 104 to secure the cover plate 104 to the proximal humerus154. The K wires 110, 112 can be inserted through the pin holes 128, 148before, when, or after the cover plate 104 is secured to the main plate102. As discussed above, the K wires 110, 112 can be inserted throughthe pin holes 128, 148 to hold bone fragments together. The pin hole 148can be aligned with the bone filler 178 when the cover plate 104 coversthe window 130 such that the K wire 112 can act as scaffolding for thebone filler when the K wire 112 is inserted in the pin hole 148. The Kwires 112, 114 can be used to provisionally fix bone fragments and canbe removed when bone screws 106, 108 have been installed to secure theplates 102, 104, respectively, to the proximal humerus 154 and therebyfix the bone fragments.

The set screws 114 can be used to secure the cover plate 104 to the mainplate 102. The set screws 114 are inserted into the partial holes 132 ofthe main plate 102 and into the partial counterbores 152 of the coverplate 104. As best shown in FIG. 10, the heads of the set screws 114 canextend into the partial counterbores 152 of the cover plate 104 tofasten the cover plate 104 without harming soft tissue.

With particular reference to FIG. 11, the bone plate assembly 100′ caninclude a first or main plate 102′ having a beveled edge 184 and asecond or cover plate 104′ having a beveled edge 186. The beveled edge184 of the main plate 102′ can engage the beveled edge 186 of the coverplate 104 to secure the cover plate 104′ in all directions except for inthe lateral direction away from the proximal humerus 154. In thisregard, the set screws 114 can be inserted into partial holes 132′ inthe main plate 102′ and into partial counterbores 152′ in the coverplate 104′ to secure the cover plate 104′ to the main plate 102′ in thelateral direction. The bone plate assemblies 100, 100′ can include anycombination of the slide mechanism 136, the set screws 114, and thebeveled edge 184 to secure the cover plates 104, 104′ to the main plates102, 102′.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present disclosure. One skilled in the art willreadily recognize from such discussion, and from the accompanyingdrawings and claims, that various changes, modifications and variationscan be made therein without departing from the spirit and scope of thedisclosure as defined in the following claims. For example, the boneplate assembly 100 can include features of the bone plate assembly 100′and the bone plate assembly 100′ can include features of the bone plateassembly 100.

What is claimed is:
 1. A proximal humeral plate assembly comprising: afirst plate defining a window, the first plate having a first majorsurface adapted to conform to a native bone structure; a coupler formedon a second major surface of the first plate opposite the first majorsurface; a second plate adapted to engage a mating surface on thecoupler and to cover the window, the second plate including throughholes adapted to receive bone screws, the second plate further adaptedto conform to the native bone structure; and a guide adapted to engagethe mating surface on the coupler and to guide at least one of a cuttingtool and a dilation tool, the engagement between the guide and themating surface on the coupler securing the guide to the first plate. 2.The bone plate system of claim 1, wherein mating surface on the coupleris adapted to slidingly receive the guide.
 3. The bone plate system ofclaim 1, wherein the guide is adapted to align the at least one of thecutting tool and the dilation tool at a predetermined angle with respectto the first plate upon engagement with the mating surface.
 4. The boneplate system of claim 1, wherein the guide includes a hollow shaft sizedto receive the at least one of the cutting tool and the dilation tool.5. The bone plate system of claim 1, wherein the window is non-circularand has a length extending generally parallel to a longitudinal axis ofthe first plate.
 6. The bone plate system of claim 5, wherein the firstplate includes an I-shaped cross-section proximate to longitudinal sidesof the window.
 7. The bone plate system of claim 1, wherein the couplerincludes an L-shaped cross section.
 8. The bone plate system of claim 1,wherein the coupler and the first plate define a longitudinal channeladjacent to the window.
 9. The bone plate system of claim 8, wherein theguide includes a base adapted to slidably engage the longitudinalchannel.
 10. The bone plate system of claim 1, wherein the second plateincludes a pin hole oriented to receive a pin at an angle.
 11. The boneplate system of claim 1, wherein the first plate includes a firstpartial hole and the second plate includes a second partial hole, thefirst partial hole and the second partial hole being adapted to receivea set screw to fix the second plate to the first plate.
 12. The boneplate system of claim 1, wherein the first plate includes a firstbeveled edge and the second plate includes a second beveled edge, thefirst beveled edge and the second beveled edge being adapted to engageeach other to secure the second plate relative to the first plate. 13.The bone plate system of claim 1, wherein the engagement between theguide and the mating surface on the coupler movably secures the guide tothe first plate.
 14. The bone plate system of claim 1, wherein thesecond plate is sized to fit within the window.
 15. The bone platesystem of claim 1, wherein an outer perimeter of the second plateconforms to an inner perimeter of the window.
 16. A proximal humeralplate assembly comprising: a first plate having a bone-engaging firstsurface and an opposed second surface, the first plate defining a windowextending through the first and second surfaces, the bone-engaging firstsurface adapted to conform to a proximal humerus; a slide mechanismformed on the opposed second surface of the first plate; a second plateslidably engaged with a mating surface on the slide mechanism andsupported by the first plate within the window, the second plateincluding through holes adapted to receive bone screws, the second platefurther adapted to conform to the proximal humerus; and a guide adaptedto engage the mating surface on the slide mechanism and to guide atleast one of a cutting tool and a dilation tool, the engagement betweenthe guide and the mating surface on the slide mechanism securing theguide to the first plate.
 17. The proximal humeral plate assembly ofclaim 16, wherein the guide is adapted to slidably engage the matingsurface on the slide mechanism.
 18. The proximal humeral plate assemblyof claim 16, wherein the mating surface on the slide mechanism and thesecond surface of the first plate define a longitudinal channel adjacentto the window.
 19. The proximal humeral plate assembly of claim 18,further comprising a rail formed on the second plate and adapted toengage the longitudinal channel.
 20. The proximal humeral plate assemblyof claim 16, wherein the engagement between the guide and the matingsurface on the slide mechanism movably secures the guide to the firstplate.
 21. The proximal humeral plate assembly of claim 16, wherein thesecond plate is sized to fit within the window.
 22. The proximal humeralplate assembly of claim 16, wherein an outer perimeter of the secondplate conforms to an inner perimeter of the window.
 23. A proximalhumeral plate assembly comprising: a first plate having a bone-engagingfirst surface and an opposed second surface, the first plate defining awindow extending through the first and second surfaces, thebone-engaging first surface adapted to conform to a proximal humerus; aslide mechanism formed on the opposed second surface of the first plate;a second plate configured to slidably engage a mating surface on theslide mechanism, the second plate being sized to fit within the windowand having an outer perimeter that conforms to an inner perimeter of thewindow such that the second plate covers the window when the secondplate is placed within the window, the second plate including throughholes adapted to receive bone screws, the second plate having abone-engaging surface adapted to conform to the proximal humerus; and aguide adapted to engage the mating surface on the slide mechanism and toguide at least one of a cutting tool and a dilation tool, the engagementbetween the guide and the mating surface on the slide mechanism securingthe guide to the first plate to prevent movement of the guide in adirection perpendicular to the first and second surfaces of the firstplate.